This invention relates generally to improvements in and relating to two and four cycle internal combustion engines, and more particularly it relates to improved spark plugs for use therewith.
For the internal combustion engines of the above kind, the fuel air ratio is so designed for attaining maximum ignitability, thereby the fuel/air mixture being rather poor in its oxygen content in comparison with that which is necessary for the realization of optimal and perfect combustion of the fuel component.
Various proposals have, therefore, been made for introducing certain amount of secondary air into the engine cylinders.
Conventionally for this purpose, an auxiliary combustion chamber having a secondary air inlet is provided, preferably in the cylinder cover or on the piston head. As an alternative proposal, a swirling auxiliary chamber is provided for the similar purpose. As a still further proposal, two ignition plugs are provided in place of the regular single one and per engine cylinder.
In these cases, however, the regular design of the engine cylinder, especially the cover thereof, must be modified so as to introduce the secondary air.